1. Field of the Invention
The present invention relates to a method of manufacturing an electronic component, and particularly to a method of manufacturing an electronic component including the step of cutting, along predetermined cutting lines, a mother substrate, having an electrode arrangement which is surface coated with a coating material, so as to obtain an electronic component device having an electrode which is exposed at a cut end surface.
2. Description of the Related Art
A chip type coil component including a thin film coil pattern (conductor pattern) disposed on the surface of a substrate is manufactured via a process including a step of cutting, at predetermined positions, a mother substrate 53 including a plurality of thin film coil patterns 51 disposed thereon and having a surface coated with an insulating protective film (coating material) 52, so as to obtain elements 54, for example, as shown in FIG. 9.
The insulating protective film 52 is made of, for example, a resin material such as polyimide or the like to provide surface smoothness, insulation quality, heat resistance, and adaptability for fine processing required for miniaturization of a chip component.
A known method of cutting the mother substrate 53 at the predetermined positions into individual components 54 includes a breaking step using a scriber. However, this method uses a cleavage function, and thus coating of the insulating protective film 52 on scribing lines makes cutting impossible, and requires cutting margins 55 (FIG. 9) to be provided around the insulating protective film 52.
In a chip type electronic component requiring miniaturization, particularly a chip type coil component having a conductor pattern such as a thin film coil pattern provided on the surface of a substrate, in order to maintain and improve performance, it is critical to ensure a large area for forming the conductor pattern. However, with the above scribe breaking technique for cutting the mother substrate, it is very difficult to ensure an area that is sufficient for the formation of the conductor pattern. Therefore, it is impossible to sufficiently satisfy the requirement for miniaturization.
Another known method of cutting the mother substrate at the predetermined positions into the respective components includes a step of cutting the mother substrate by using a dicing blade. This dicing method has excellent processing accuracy and is capable of cutting the insulating protective film 52 at the same time, thereby eliminating the need for the cutting margins. It is thus possible to form the insulating protective film 52 over the entire surface of the mother substrate, as shown in FIG. 10. The dicing method thus has the advantage that the conductor pattern 51 can be formed up to the periphery of a chip, and a wide area can be used for forming elements, as compared with the scribe breaking method.
Recently, in order to maximize the use of the substrate surface, the insulating protective film has been formed over substantially the whole area of the substrate, as shown in FIG. 10, and a connecting electrode 58 connected to an external terminal has been arranged at the end of each of the components 54 and exposed from the cut end surface by cutting (dice cutting) using a dicing blade so as to be positioned to be easily connected to an external electrode.
However, a chip type coil component in which the conductor pattern such as the thin film coil pattern is disposed on the surface of the substrate has recently been required to have characteristics for radio frequencies. Thus, it has been essential to decrease the dielectric constant of the material of the substrate. Therefore, the substrate made must be made of low-dielectric-constant materials such as glass, glass ceramics, composite mica ceramics, ferrite, and the like. However, such low-dielectric-constant materials experience chipping, cracking or peeling in the substrate below the connecting electrode in the cut plane due to cutting impact which causes deterioration in reliability due to poor connection with the external electrode or open failure due to peeling between the substrate and the connecting electrode.
FIGS. 11A and 11B are schematic drawings each showing a state wherein chipping C and peeling D occur when the mother substrate 53 with the surface having the conductor pattern 51 (the connecting electrode 58) disposed thereon and covered with the insulating protecting film 52 is cut by dicing.